Modifications of nutrient selection induced by naloxone in rats.
Total caloric intake and dietary self-selection of the three macronutrients protein, fat, and carbohydrate were examined in male rats maintained on a 6-h feeding schedule following the administration of the opioid antagonist naloxone HCl (0.1, 1.0, and 10.0 mg/kg IP). Total caloric intake (calculated as the sum of caloric intakes from each of the macronutrients) was decreased for up to 2 h following naloxone administration. By the end of the 6-h feeding period, however, no differences in total caloric intakes were observed as a function of naloxone injections. Examination of intakes of the individual macronutrients revealed that naloxone differentially affected fat, carbohydrate, and protein consumption. Across the 6-h feeding period, animals consumed less calories from the fat ration following all three doses of naloxone than after saline injections. Carbohydrate intake was decreased up to 2 h following naloxone injections, but returned to control values by the end of the 6-h feeding period. Protein intake, in contrast to fat and carbohydrate intakes, did not vary as a function of naloxone administration. Results of the present examination are contrasted with patterns of dietary self-selection observed following morphine administration.
D000818:Animals; D004032:Diet; D004040:Dietary Carbohydrates / Q000008:administration & dosage; D004041:Dietary Fats / Q000008:administration & dosage; D004044:Dietary Proteins / Q000008:administration & dosage; D005518:Food Preferences / Q000187:drug effects*; D008297:Male; D009270:Naloxone / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D013997:Time Factors
D004040:Dietary Carbohydrates; D004041:Dietary Fats; D004044:Dietary Proteins; D009270:Naloxone